What hormone is responsible for sodium reabsorption in the kidney?

Aldosterone is the hormone responsible for sodium reabsorption in the kidneys. It is produced by the adrenal glands and plays a crucial role in regulating electrolyte balance and blood pressure. Aldosterone acts primarily on the distal convoluted tubule and the collecting ducts of the nephron, where it promotes the reabsorption of sodium ions back into the bloodstream. This reabsorption process is essential for maintaining fluid balance, blood volume, and overall homeostasis in the body.

In addition to its role in sodium reabsorption, aldosterone also facilitates the excretion of potassium ions, which helps to maintain the balance of electrolytes. The action of aldosterone is part of the renin-angiotensin-aldosterone system (RAAS), which is activated in response to low blood pressure or low sodium levels, further emphasizing its significance in regulating blood pressure and electrolyte homeostasis.

The other hormones mentioned do not primarily function in sodium reabsorption. Antidiuretic hormone (ADH) is mainly involved in regulating water reabsorption in the kidneys, erythropoietin primarily stimulates red blood cell production in response to hypoxia, and renin is an enzyme that activates the RAAS but does not directly reabsorb sodium.